Electrolytic production of sodium alloys.



t 'rnun' nsncnor'r, or Lennon, anon w htncrnrrrc 1;,

Menace.

Ito brewing.

To all 'wlwm itmay concern: I

Be it known that I, EDGAR ARTHUR ASH- cnor'r, a subject of the King of Great Britain,. and residing at 99 Buckingham Palace 1 to be taken up at the cathode by molten heavy metal such for exampleas lead. It

has also been proposed to use, in the arts,

the alloys of the alkali metals with a heavy metal instead of using the pure metals. The electrolysis takes place as is known in accordance with the following formula:

'Ihe hypothetic radical hydroxyl reacts at once in accordance with the following formula: 2 (0H) =II O+U tion of the water absor ed by the melt must be consumed, or what comes to the same thing, only 1 molecular proportion of sodium is formed out of 2 molecular proportions of sodium the second molecular proportion of sodium being consumed in decomposing the water formed at the anode and this reduction of the current eficiency to half that theoretically possible, is-characteristic of all the processes in which caustic alkalis havebeen electrolyzed by means of insoluble'anodes. For instance, in the Castner process described in the specification of German Patent No. 58121 the practical current elficiency is lower than 40 per cent. and the operation is carried out at a temperature of 350 centigrade. Castner says in his specification:

In orderto ifiure a suitable yield of alkali metal for the current supplied, it is necessary-that the tem erature of the electrolyte should not be a lowed to exceed the melting point of thecaustic alkali used by nore than 20 ,centigrade, that is when treating caustic soda which melts. at about 310? centigrade, the temperature of the electro- Specification of Letters Patent.

nucrron on son]: armors.

Patented Now 23, twill,

Application filed November at, an. Serial no. scarce.

lyte should be kept below 330 centigrade. The same should be observed for caustic potash, or a mixture of both hydroxids, whlch has a lower melting point than the caustic jpotash and caustic soda taken each by itsel v Lorenz describing a phenomenon of olarization' has drawn attention to the in uence of the temperature and of the voltage requlred for the decomposition (Lorenz, Electrolysis of Molten Salts, published by Knapp, I-Ialle 1906, part 3, pages 278 and l 279). Other experimenters have stated that, for the successful electrolysis of, for instance, caustic soda, the temperature must be below 400 centigrade.

While the above prescriptions for the production of pure sodium have hitherto not been contradicted, I have ascertained that, for the production of lead sodium the conditions are difierent and that by the use of a higher temperature the extra consumption of energy required for the decomposition ofv water can be avoided, partly, or wholly. According to my invention the water is partly, or wholly, expelled as such at a I high temperature, so that mainly oxygen and aqueous steam escape from the electrolyzing vessel and not oxygen and hydrogen as in the hitherto known processes. or less, complete carrying out of my new process, I carry on the electrolysis at a temperature of, or over, 400centirgrade, and I observe the following important precautions, all of which tend to the production of a result as perfect as possible. Firstly that the layer of the alkali h droxid above the heavy metal alloy, shall e comparatively thin; secondly, that both the electrolyte and the alloy shall be kept in For the more,

motion, for instance by means of magnetic stirring, and thirdly, that the operation shall be carried out with a current density as lll h as possible at the anode. The alloys 0 lows: A cathode of molten. heavy metal, for instance lead, with about from 6, to 12 per cent. of sodium is placedin a circular shal vlow flat cell provided with properly arranged inlet and overflow the Cast ner process employed, especially for tion of British Letters Patent No. 5648 A. D.

1905 granted to me). By these means the formation in the alloy, of layers of different specific gravities and .of deposits on the surface of the cathode is avoided while the escape of the aqueous steam is promoted. By working in this manner, yield efliciencies of current of from 60, to 80 per cent. and more, can be obtained. As in most processes of this kind the heat is produced by the electric current and regulatedby a suitable selection of the current density. The anode can be of nickel, or any other suitable metal, and is preferably so arranged that the current enters at a row of points distributed in a suitable manner over the area of the cathode and connected with an annular plate.

The apparatus which is described in the.

aforesaid specifications of my previous British Patents Nos. 1001 to 1005 'A. 'D. 1912 is very suitable for the purpose in view if the earthenware lining be omitted and a lining of copper, nickel or other suitable metal be substituted and the graphite anode be 5 replaced by the aforesaid annular anode plate of nickel. The pipes for the escape of chlorin from the aforesaid apparatus are in the present process used for carrying away the spray of alkali which is entrained with the steam and would contaminate the air.

Such spray is condensed in a suitable condensation chamber. From time to time the dirt which has deposited in the cell must be removed, as this .dirt would otherwise accumulate and disturb the course of the electrolysis. It is lmown that, for all; such processes, apparatus as large as possible is of importance for economical operation. The process herein described is especially suitable for the employment of large units. It is thus preferable to work a double cell apparatus with 10,000 amperes. If for instance. metallicsodium is produced in the secondary cell, a total voltage of about 5 volts is-used,

including of course, the heat energy required for heating both cells. It is known that in the production of sodium, only apparatus of about 1250 amperes, or thereabout have been used and that a large number of cells are required to produce a'given quantity of metal.

British specification No. 228 of A.

In the process herein described more than ten times such quantity of sodium can be readlly manufactured. Not only is the labor required less, but the consumption of energy is also much less for a given quantity of product.

It is obvious that the 'hereinbefore described process can be used for the production of alkali-metal alloys without departing from the invention if such alloys are to be used as final products for industrial purposes. It is however likewise obvious that the process can be used directly in combination with known methods for the production of valuable products such as alkali metals, amids, cyanamids, cyanids and the like,in the secondary cell attached to the said apparatus, with, or without, the use of the electrolysis as described for instance in the D. 1910.

What I' claim is 1. The process of producing alloys of sodium and heavier metals which consists in subjecting an electrolyte of molten sodium hydroxid to electrolysis between a suitable anode and a cathode of a .molten heavy metal, the electrolysis being carried out'at a temperature of about 400 centigrade.

' 2. The process of producing alloys of sodium and heavier metals which consists in subjecting an electrolyte of molten sodium hydroxid to electrolysis between a suitable anode and a cathode of a molten heavy metal, the electrolysis being effected at a temperature of at least substantially 400 centigrade.

3. The process of producing alloys of sodium and heavier metals which consists in subjecting an electrolyte of molten sodium hydroxid to electrolysis between a suitable anode and a cathode of a molten heavy metal, maintaining the sodium hydroxid in a thin layer on the cathode during electrolysis and effecting the electrolysis at a temperature of about 400 centigrade.

4. The process of producing alloys of sodium, and heavier metals. which consists in subjecting an electrolyte of molten sodium hydroxid to electrolysis between a suitable anode and a cathode of a molten heavy metal at a temperature of about 400 centigrade while maintaining a high current density at the anode.

5. Theprocess of producing alloys of sodium and heavier metals which consists in subjecting an electrolyte of molten sodium hydroxid to electrolysis between a suitable anode and a cathode of a molten heavy metal at a temperature of about 400 centigrade, while maintaining the electrolyte and cathode metal in motion during electrolysis.

6. The process of producing alloys of sodium and heavier metals which consists in subjecting an electrolyte of molten sodium hydroxid to electrolysis between a suitable 1,1e1,tet I m anode and a cathode of a molten heavy In testimony whereof I have signed my metal, maintaining the electrolyte in a thin name to this specification in the presence of layer, while keeping the electrolyte and two subscribing witnesses.

cathode in motion, the operation being ef- EDGAR ARTHUR ASHCROFT. fected with a high current density at the Witnesses:

anode and. at a temperature of about 400 WALTER WILLIAM EDGECOMBE, centigrade. JOSEPH HENRY WILLS. 

